Surfaces to be coated with polymers must generally be subjected to a comprehensive, that is, time-consuming pre-treatment in order to achieve a sufficiently firm adhesion. A pre-cleaning of the surface to be coated with a suitable chemical solvent is usually carried out initially in order to remove, for example, contamination by grease, oils, release agents, fingerprints or dust particles. This is usually followed by purely mechanical pre-treatment by sanding in order to enlarge the surface area of the substrate available for adhesion of the polymer or paint by increasing the surface roughness. Sanding of the surface can be carried out with different grain sizes manually and/or in a motor-driven manner by suitable machines such as, for example, a random orbit sander or belt sander. In order to reduce environmental pollution, extraction devices are frequently used during the sanding process. In order to again remove sanding residue from the surface, which is never completely avoidable notwithstanding any extraction, a further cleaning of the surface with a solvent must be carried out after the sanding process.
This conventional procedure during the pre-treatment of a surface to be painted on the one hand has the disadvantage that the working areas used for the painting work are contaminated with solvent vapour which evaporates during the substrate cleaning processes. In addition, several time-intensive cleaning and sanding procedures are generally required for preparation of the actual painting process, sanding dust being emitted into the environment by these procedures despite the extraction systems.
Methods for pre-treatment of surfaces to be painted are known from the prior art in order to improve the adhesion properties on the surface by treatment with a plasma jet. An apparatus and a method for plasma treatment of surfaces is known, for example, from DE 699 29 271 17 whereby, inter alia, the bond strength of wires on the plasma-treated surface can be increased during chip fabrication. However, this method cannot be applied to the treatment of large-scale components which are additionally formed with a plurality of different materials and/or connection means.